This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. Section 119 from an application for xe2x80x9cPlanar Light Waveguide Circuit with Landmarks,xe2x80x9d filed in the Korean Industrial Property Office on Dec. 30, 2000 and there duly assigned Serial No. 2000-87199.
1. Field of the Invention
The present invention relates generally to a planar light waveguide circuit, and in particular, to a planar light waveguide circuit with landmarks and a method of manufacturing the same.
2. Description of the Related Art
Recently, active researches have been conducted on an optical element integration technology of manufacturing a light waveguide on a planar substrate for the purpose of optical signal processing, such as dividing, modulating, switching, and multiplexing of optical signals. To manufacture this type of light waveguide circuit, various techniques including designing, manufacturing, and packaging, are required.
A general light waveguide component is equivalent to a light transmission line for propagating optical waves with a small loss by confining the optical waves within the waveguide component in a longitudinal direction. To achieve this, the light waveguide could be formed in a substrate with a high refractive index and a cladding with a low refractive index, where the cladding is surrounded by the core.
Now, a process for packaging the conventional planar light waveguide circuit will be described below with reference to FIGS. 1 and 2. As illustrated in these figures a conventional planar light waveguide circuit (PLC) 10 is packaged in way that the PLC 10 is in alignment with optical fiber blocks 11 and 12, which are used for receiving and outputting a light beam from or to the PLC 10. The PLC 10 is manufactured by depositing a multi-layer silica or polymer film in a silicon or quartz substrate for dividing the light strength and wavelength, changing the light path, and adjusting the light strength using a refractive index difference between the core and the cladding surrounding the core. The optical fiber blocks 11 and 12 serve to support optical fibers 13 and 14, respectively, and are manufactured by forming a V-groove on the silicon substrate.
Accordingly, the optical fiber blocks 11 and 12 arrange the optical fiber 13 and the ribbon-type optical fiber 14 in the V-groove, thus fixing them to the planar light waveguide circuit 10. Here, the PLC 10 is aligned with the optical fiber blocks 11 and 12, located at both ends thereof, through a precise position control device and then fixed (or glued) to the aligned optical fiber blocks 11 and 12 by applying the glue 17 to the contact areas. Here, an ultraviolet or thermo-setting glue is typically used for the glue 17. Alternatively, the PLC 10 can be also fixed to the optical fiber blocks 11 and 12 through a welding operation instead of using the glue 17. Thereafter, the PLC 10 is packaged in a metal or plastic housing 15, and furthermore, the PLC 10 may be subject to a hermetic sealing as occasion demands. In addition, when the light waveguide circuit is required to adjust its temperature, an external power connector is connected to the housing 15 to provide a current to the light waveguide circuit. In FIG. 2, reference numeral 16 denotes a power lead.
However, in the above alignment connection process, it is important to cut the sections (or profiles) of the light waveguide circuit and the optical fiber blocks precisely to obtain optimal performance. The section cutting process includes a combination of the cutting technique using a blade and the polishing technique using abrasives. An accuracy of the section cutting process is closely related to a coupling loss, which occurs at the junction where the light waveguide circuit is coupled to the optical fiber blocks. In particular, the sloped cut section typically causes a decrease in the uniformity of an insertion loss. Therefore, a separate process for measuring the accuracy of the section cutting process is required in the prior art. If the cutting process is inaccurate, the process must be repeated and sometimes, if excessively cut, the light waveguide circuit must be discarded.
The present invention relates to a planar light waveguide circuit capable of minimizing a coupling loss, which occurs when the planar light waveguide circuit is being coupled to the optical fiber blocks, by accurately measuring the slope of a cut section of the planar light waveguide circuit and correcting the slope end of the optical fiber blocks.
According, the present invention provides a planar light waveguide circuit with landmarks used for aligning the planar waveguide circuit to the optical fiber block components.
The present invention relates to a planar light waveguide circuit, which includes a plurality of landmarks arranged along one end of the planar light waveguide circuit at intervals of a predetermined gap so as to increase the uniformity of a coupling loss occurring when connecting the planar light waveguide circuit in alignment with the optical fiber blocks.
Preferably, the landmarks are formed onto the planar light waveguide circuit so as to enable an operator to monitor a permissible angle error when cutting the side of the planar light waveguide circuit.
Preferably, Arabic numerals or specific symbols are noted in association with the landmarks indicated on the planar light waveguide circuit to assist the operator distinguish relative position of the landmarks during the cutting process.